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vhost: modify vhost_log_write() for broader users

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Currently, the only user of vhost_log_write() is vhost-net. The 'len'
argument prevents logging of pages that are not tainted by the RX path.

Adjustments are needed since more drivers (i.e. vhost-scsi) begin using
vhost_log_write(). So far vhost-net RX path may only partially use pages
shared via the last vring descriptor. Unlike vhost-net, vhost-scsi always
logs all pages shared via vring descriptors. To accommodate this,
use (len == U64_MAX) to indicate whether the driver would log all pages of
vring descriptors, or only pages that are tainted by the driver.

In addition, removes BUG().

Suggested-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Message-Id: <20250403063028.16045-5-dongli.zhang@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Dongli Zhang 2025-04-02 23:29:49 -07:00 committed by Michael S. Tsirkin
parent a5806cd506
commit 41cff026cf
1 changed files with 20 additions and 8 deletions
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28
drivers/vhost/vhost.c
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@ -2304,6 +2304,19 @@ static int log_used(struct vhost_virtqueue *vq, u64 used_offset, u64 len)
return 0;
}
/*
* vhost_log_write() - Log in dirty page bitmap
* @vq: vhost virtqueue.
* @log: Array of dirty memory in GPA.
* @log_num: Size of vhost_log arrary.
* @len: The total length of memory buffer to log in the dirty bitmap.
* Some drivers may only partially use pages shared via the last
* vring descriptor (i.e. vhost-net RX buffer).
* Use (len == U64_MAX) to indicate the driver would log all
* pages of vring descriptors.
* @iov: Array of dirty memory in HVA.
* @count: Size of iovec array.
*/
int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
unsigned int log_num, u64 len, struct iovec *iov, int count)
{
@ -2327,15 +2340,14 @@ int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
r = log_write(vq->log_base, log[i].addr, l);
if (r < 0)
return r;
len -= l;
if (!len) {
if (vq->log_ctx)
eventfd_signal(vq->log_ctx);
return 0;
}
if (len != U64_MAX)
len -= l;
}
/* Length written exceeds what we have stored. This is a bug. */
BUG();
if (vq->log_ctx)
eventfd_signal(vq->log_ctx);
return 0;
}
EXPORT_SYMBOL_GPL(vhost_log_write);